Tires provided with a plurality of main grooves extending in a tire circumferential direction in a tread portion are normally used as wet tires for racing. It is recognized that superior running performance of such tires on wet road surfaces are exhibited based on a drainage capability of the main grooves. However, in high speed races, an amount of water pushed ahead increases since water cannot be drained by the main grooves in tires having a tread pattern with main grooves extending in the tire circumferential direction as a main constituent, which results in an occurrence of a hydroplaning phenomenon. Also, in races with Gran Turismo (GT) touring cars having tire housings, there is an adverse effect whereby water remains in tire housings when tires having a tread pattern with main grooves extending in the tire circumferential direction as the main constituent are used. Thus, a groove arrangement that can drain water on road surfaces in a tire lateral direction is required.
As a wet tire for racing meeting such a demand, a tire is provided including, in the tread portion, a main groove that is in a tread center position and that extends in the tire circumferential direction, a plurality of first angled grooves that is in communication with the main groove and that extends at an angle, in a direction opposite a rotational direction, from the tread center position towards each shoulder side, and a plurality of second angled grooves that is not in communication with the main groove and that extends at an angle, in the same direction as the respective first angled grooves, while intersecting at least three of the first angled grooves, wherein a plurality of blocks is partitioned by the main groove and the angled grooves (for example, see Japanese Patent Publication (A) No. 2007-238060).
However, when the tread portion is partitioned into a plurality of blocks by the main groove and the angled grooves as disclosed above, a rigidity of the tread portion deteriorates. Since a large load is applied to tires when braking and when cornering in racing, there is a problem that a necessary braking performance and cornering performance on wet road surfaces cannot be exhibited when the rigidity of the tread portion is insufficient.